Tooth canals are currently filled by the "lentula" method or by using gutta-percha cones. These two methods are satisfactory but fill the lateral canals randomly and in any case do not fill the canaliculi. Processes involving the injection of hot gutta-percha appeared a few years ago on the American market, but the results do not yet seem to be convincing. The process is very difficult to apply in the case of canals treated by the hydraulic method, as described in U.S. Pat. No. 4,993,947.
The latter patent describes a vacuum filling process which has shown a few shortcomings. The friction of the plunger of the syringe has to be compensated by a slight pressure on said plunger, which runs the risk of causing overflowing at the apex. Filling paste often passes into the suction tube connecting the nozzle to the vacuum pump.
The vacuum filling of devitalized teeth was proposed as long ago as 1958 (Prof. Dr.med.Dr.med.dent. Gustav Korkhaus and Dr.med.dent. Rudolf Alfter: Die Vakuumwurzelbehandlung (Vacuum Treatment of Roots), Forschungsberichte des Wirtschaft- and Verkehrsministeriums Nordrhein-Westfalen; Westdeutscher Verlag, Cologne and Opladen, 1958). However, the equipment used at the time was cumbersome and rather inefficient and was poorly suited to dental technique. The three-way valve was not easy to use and the dead volumes were very large.